Process and device for avoiding strapping-caused downtime on machine for strapping packages

ABSTRACT

The invention concerns a process and a device for avoiding interruptions of operation caused by the strapping, on machines for the strapping of packing elements. The process is characterized by a second strapping coil with further strapping, and in that the leader of one of the two strappings is constantly kept at a standby position in the machine from which, upon removal of the other strapping from the strapping guideway, it is automatically fed to the strapping guideway. The device is characterized in that the feed system is preceded by a switch with two strapping guideways for a leader section for each one of the two strappings, with a strapping feed for the alternative introduction of one of the two strapping leaders into the feed system. A first drive system is provided within the vicinity of the strapping guideways for selectively introducing one of the strapping materials into the feed system, while a second drive system is provided within the vicinity of the supply coils of the strapping materials for selectively engaging one of the supply coils in order to retract or withdraw a damaged or depleted strapping material from the feed system and permit a second one of the strapping materials to be introduced into the feed system.

FIELD OF THE INVENTION

The invention generally relates to strapping machines or systems, andmore particularly is directed toward an apparatus and a process foravoiding strappingcaused downtime on machines for the strapping ofpackages, where the strapping material is stored on a supply coil.

BACKGROUND OF THE INVENTION

A process for the elimination or prevention of strapping-caused downtimeon such machines is known from DE-PS 38 25 668. In this patent, thestrapping--primarily thermoplastic synthetic strap or also steelband--contained in the machine is, in case of trouble, pulled out of themachine in a direction opposite to the feed direction of the strapping,by running the strapping coil in reverse. Therefore, in eliminating astrapping-caused malfunction, it is not necessary to perform any repairor corrective work upon the machine, but the strapping can be moreswiftly prepared for re-insertion into the machine as a result of repairwork performed upon the strapping material outside the machine. Thus,this process shortens a machine breakdown in time respects.

This prior process has proved itself extremely well. However, theduration of the work to be performed outside the machine in conjunctionwith eliminating damaged spots on the strapping can hardly beinfluenced, except for the skill applied in doing the manual work, sothat corresponding machine downtime must be accepted.

OBJECT OF THE INVENTION

It is therefore a primary objective underlying the invention to providea process for avoiding strapping-caused interruptions, which processenables in simple fashion a considerable further shortening of theduration of such interruptions.

SUMMARY OF THE INVENTION

The present invention solves the aforenoted problem through a processwhich is characterized by the provision of a further coil of strappingand in that the leader of one of the strappings is constantly kept readyin the machine in waiting position, from which, upon removal of theother strapping from the strapping guideway, it is automatically fed, asthe case may be, into the strapping guideway.

According to the inventive process, the machine can in the event of astrapping-caused interruption automatically pull the damaged strappingout of the machine and continue its operation, without operatorintervention, with the second strapping.

Interruptions caused by the strapping now need to last only up until thestrapping contained in the machine has been pulled out of the machinebecause--once this has taken place--the strapping leader of the furtherstrapping already disposed at the waiting position can be automaticallyfed to the strapping guideway. This shortens the duration of theinterruption by the time which otherwise was necessary for repairing thestrapping leader. During this time, which is still need to repair theoriginally damaged strapping, the machine already operates with thesecond strapping. Additionally, this has the advantage that the personperforming the work on the damaged strapping may allow himselfsufficient time for performing the job with particular care.

A strapping-caused interruption may also, occur when the strappingsupply of a coil is depleted. Here, the inventive process results in thesame advantages, because a new strapping coil can during the operationof the other strapping be installed and placed in its inventive standbyposition.

It is basically already known to store a second strapping coil at areserve strapping station. But the strapping of that coil is containedexclusively on the coil and is in no specific arrangement operativelyrelated to the strapping system; when needed, the strapping needs to beunwound from each supply in an unwieldy and time-consuming fashion, justas before, and fed to the machine. Therefore, this prior art merelyprovides for a strapping supply to be kept near the machine.

The invention also concerns a machine for the strapping of goods to bepacked, with a rotatably driven and, as the case may be, breakablestrapping coil, and with a feed system for the strapping. The objectiveis to provide a machine whose capacity is increased due to, in timerespects, minimized interruptions caused by the strapping.

The invention solves the aforenoted problems by arranging before thefeed system a switch with two strapping guideways, each for a leader ofthe two strappings, and with a strapping feed for alternativeintroduction of one of the two strapping leaders into the feed system.

The switch controls the two strappings in such a way that--depending onthe switch position--one of the two strappings is gripped by the feedsystem while the other, standing by, waits to be used. Thus, theinvention has the particular advantage that upon occurrence of aninterruption, as a result of a defect or disturbance of the run of theone strapping, the packing cycle can be continued immediately, that is,upon removal of the first strapping from the machine, and with the leadsection of the second strapping introduced into the strapping feed.Besides, the switch ensures by means of its controllability that theleader of the one strapping, merely "held in reserve," cannotinadvertently proceed into the path of the strapping which is in use.

In accordance with a preferred embodiment of the invention, the switchpreceding the feed system is so arranged that the two strappingguideways converge from two spatially separated entrance gaps toward thefeed system while the strapping feed is arranged near the strappingentrance gaps. The advantage of this is that the strapping leaders onlyneed to be pushed a short distance into the strapping guideways forbeing fed, when needed, by the strapping feed directly into the feedsystem.

In a particularly preferred embodiment, the strapping feed--as the casemay be, from an operationally neutral position--acts alternatively onthe strapping contained in the one or on that contained in the otherstrapping guideway. Therefore, by means of only a single strapping feed,the respective one of the strapping leaders in the strapping guidewaysis in favorable fashion moved into the feed system.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features, and attendant advantages of the presentinvention will become more fully appreciated from the followingdescription of the invention, with the aid of an embodiment illustratedin the accompanying drawings, in which like reference charactersdesignate like or corresponding parts throughout the several views, andwherein:

FIG. 1 is a schematic view of a machine for strapping goods to bepacked;

FIG. 2 is a section of FIG. 1, where the two strapping coils have beenrotated 90°, and

FIG. 3 is an enlarged illustration of the area of the machine circled inFIG. 2.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Contained on the machine housing 11 on a strapping machine referenced 10overall is an essentially sealed strapping guide channel 12 throughwhich, and around a packing element (not shown), a strapping 13 is fedto a sealing unit 14.

The strapping 13--normally a band of thermoplastic material or steel--iskept in supply outside the machine housing 11 on two strapping coils 15and 16, which are rotatably mounted on shafts or axles 17 arrangedhorizontally on the machine housing 11. Arranged between the strappingcoils 15 and 16, as well on the machine housing 11 and on a pivot arm19, is a drive 18 coordinated with the coils.

Referenced 20 is a strapping receiver, which in the embodiment isfashioned as a box type receiver, with an inside clearance which is onlyslightly larger than the strapping 13 is wide. The strapping 13 is fedinto the strapping receiver 20 with the aid of receiver fill feed rolls21. Arranged behind the strapping receiver 20, forwardly in the feeddirection of the strapping, are strapping retraction rolls 22 which, inturn, are preceded by strapping thrust rolls 23. The rollers 21, 22 and23 are fashioned as roller pairs driving the strapping by friction.Referenced 24 is a strapping tensioner, which here does not play aparticular role.

Arranged in front of the feed rolls 21 is a switch 26 which comprisestwo strapping guideways 25. While the strapping guideways 25 converge inthe area of the feed rolls 21, their exposed rear ends form thestrapping entrance gaps 27 for the two strappings 13. Arranged in thearea of the entrance gaps 27 is a strapping feed 28 comprised of twospatially fixed rolls 29 and two pivotal rolls 30 which are coupled toone another in the fashion of a belt drive. Coordinated with eachstrapping guideway 25, between the feed rolls 21 and the device 28, is astrapping sensor 31. Moreover, a reversing roll 32 is mounted on themachine housing 11, between each strapping coil 15, 16 and thepertaining entrance gap 27.

As FIG. 2 shows, a photoelectric cell 33 is coordinated with eachstrapping coil 15, 16. Shown schematically at 34 is a reflective surfaceon the strapping core 35, which may be formed by the core materialitself.

The first-time operation of the strapping machine 10 proceeds asfollows. To begin with, the two leader sections of the strapping 13 arethreaded through the reversing rolls 32 and inserted in the entrancegaps 27. Upon starting the machine, the leader of one strapping ispushed by the strapping feed 28, through one of the strapping guideways,between the receiver fill feed rolls 21. Next, the receiver fill feedrolls 21 surrender the strapping 13 to the strapping retraction rolls22, which at appropriate direction of rotation feed the strapping 13through the tensioning device 24 and the strapping thrust rolls 23 tothe sealing unit 14.

In a next step, due to the back-up pressure created, the receiver 20 isfilled by means of the feed rolls 21 with at least the strapping lengthnecessary for the following strapping operation. The back-up pressure iscreated by retaining the strapping leader in the sealing unit 14 whilethe receiver fill feed rolls 21 continue to feed. Next, the strappingthrust rolls 23 feed the strapping leader at high speed through thestrapping channel 12, with the front end of the strapping being clampeddown in the area of the sealing unit. The strapping 13 is then tightenedaround the packing element by means of the strapping retraction rolls22, the overlapping strapping sections are joined by the sealing unit 14and, finally, the strapping is cut off. A new strapping cycle can beginthereafter.

If disturbances now occur which are caused by the strapping, the damagedstrapping section is moved out of the machine 10. This takes place inthat the strapping coil 15 or 16, from which the strapping 13 ispresently being unwound, is driven with the aid of the drive 18(rewinder) in a direction opposite to the operationally given directionof rotation. To enable the alternative driving of both strapping coils15, 16 in the direction opposite to the regular direction of rotation,the drive 18 is mounted on a pivot arm 19 which by solenoids 36 arrangedon both sides thereof can be moved in such a way that it engages eitherthe strapping coil 15 or 16 assumes a neutral middle position.

During the pullback of the strapping 13, the strapping sensor 31coordinated with a strapping guideway 25--once the end of the strappinghas passed--automatically causes the start of the strapping feed 28,whereby the strapping leader of the strapping 13 contained on the otherstrapping coil 15 or 16 is advanced through the other strapping guideway25 to the receiver fill feed rolls 21. Next, the packing cycle describedabove can immediately be continued with the "reserve band." Downtimecaused by the strapping is considerably shortened thereby.

The process and the device also act accordingly as the strapping supplyis being depleted. For instance, as the upper strapping coil 15 is thedrawing, the strapping of which is presently being used, is depleted,the reflective performance regarding the respective photoelectric cell33 changes as soon as its beam changes over from the band to thestrapping core 35. This "strapping end ensing" leads to the retractionof the strapping 13 out of the machine 10. As soon as the respectivestrapping sensor 31 then signals its guideway 25 as being empty, thestrapping feed 28 changes over to the second strapping 13, presenting itto the strapping feed apparatus. Consequently, nearly no machinestandstill occurs either upon depletion of the strapping 13 of onestrapping supply.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the presentinvention may be practiced otherwise than as specifically describedherein.

We claim:
 1. A method for avoiding downtime interruptions of strappingoperations upon strapping machines for strapping package elements,comprising the steps of:providing a first supply coil of strappingmaterial; providing a second supply coil of strapping material;providing a first flow path for a first strapping material wound uponsaid first supply coil and leading from said first supply coil to astrapping sealing unit; providing a second flow path for a secondstrapping material wound upon said second supply coil and leading fromsaid second supply coil to said strapping sealing unit; driving one ofsaid first and second strapping materials, by a first drive means whichis selectively engageable with said first and second strappingmaterials, in a forward direction along a respective one of said firstand second flow paths from a respective one of said first and secondsupply coils to said strapping sealing unit; driving said respective oneof said first and second supply coils, by a second drive means which isselectively engageable with said first and second supply coils, in areverse direction so as to retract said one of said first and secondstrapping materials out from said respective one of said first andsecond flow paths when a flow disturbance occurs along said respectiveone of said first and second flow paths during forward driving of saidone of said first and second strapping materials along said respectiveone of said first and second flow paths; and sensing a leading endportion of said one of said first and second strapping materials, by asensing switch means, as said one of said first and second strappingmaterials is withdrawn from said respective one of said first and secondflow paths as a result of said driving of said selected one of saidfirst and second supply coils in said reverse direction by said seconddrive means in consequence of said occurrence of said flow disturbancealong said respective one of said first and second flow paths, andactuating said first drive means such that said first drive meansengages the other one of said first and second strapping materials so asto drive said other one of said first and second strapping materials insaid forward direction along the other one of said first and second flowpaths when said sensing switch means senses said withdrawal of said oneof said first and second strapping materials from said respective one ofsaid first and second flow paths, whereby downtime interruption of saidstrapping operation, due to said disturbance occurring along saidrespective one of said first and second flow paths, is minimized.
 2. Amethod for avoiding downtime interruptions of strapping operations uponstrapping machines for strapping package elements, comprising the stepsof:providing a first supply coil of strapping material; providing asecond supply coil of strapping material; providing a first flow pathfor a first strapping material wound upon said first supply coil andleading from said first supply coil to a strapping sealing unit;providing a second flow path for a second strapping material wound uponsaid second supply coil and leading from said second supply coil to saidstrapping sealing unit; driving one of said first and second strappingmaterials, by a first drive means which is selectively engageable withsaid first and second strapping materials, in a forward direction alonga respective one of said first and second flow paths from a respectiveone of said first and second supply coils to said strapping sealingunit; providing a second drive means which is selectively engageablewith said first and second supply coils for driving said respective oneof said first and second supply coils in a reverse direction so as toretract said one of said first and second strapping materials out fromsaid respective on of said first and second flow paths when said one ofsaid first and second strapping materials is depleted upon saidrespective one of said first and second supply coils; sensing depletionof said one of said first and second strapping materials, by a firstsensing switch means, upon said respective one of said first and secondsupply coils, and actuating said second drive means for driving saidrespective one of said first and second supply coils in said reversedirection so as to retract said one of said first and second strappingmaterials out from said respective one of said first and second flowpaths; and sensing a leading end portion of said one of said first andsecond strapping materials, by a second sensing switch means, as saidone of said first and second strapping materials is withdrawn from saidrespective one of said first and second flow paths as a result of saiddriving of said respective one of said first and second supply coils insaid reverse direction by said second drive means in response to saidsensing of said depletion of said one of said first and second strappingmaterials upon said respective one of said first and second supplycoils, and actuating said first drive means such that said first drivemeans engages the other one of said first and second strapping materialsso as to drive said other one of said first and second strappingmaterials in said forward direction along the other one of said firstand second flow paths when said second sensing switch means senses saidwithdrawal of said leading end portion of said one of said first andsecond strapping materials from said respective one of said first andsecond flow paths, whereby downtime interruption of said strappingoperation, due to said depletion of said one of said first and secondstrapping materials upon said respective one of said first and secondsupply coils, is minimized.
 3. Apparatus for strapping package elements,comprising:a first supply coil of strapping material; a second supplycoil of strapping material; a first flow path for a first strappingmaterial wound upon said first supply coil and leading from said firstsupply coil to a strapping sealing unit; a second flow path for a secondstrapping material wound upon said second supply coil and leading fromsaid second supply coil to said strapping sealing unit; first drivemeans selectively engageable with said first and second strappingmaterials for driving a selected one of said first and second strappingmaterials in a forward direction along a respective one of said firstand second flow paths from a respective one of said first and secondsupply coils to said strapping sealing unit; second drive meansselectively engageable with said first and second supply coils fordriving a selected one of said first and second supply coils in areverse direction so as to retract one of said first and secondstrapping materials out from a respective one of said first and secondflow paths when a flow disturbance occurs along said respective one ofsaid first and second flow paths during forward driving of said one ofsaid first and second strapping materials along said respective one ofsaid first and second flow paths; and sensing switch means for sensing aleading end portion of said one of said first and second strappingmaterials as said one of said first and second strapping materials iswithdrawn from said respective one of said first and second flow pathsas a result of said driving of said selected one of said first andsecond supply coils in said reverse direction in response to saidoccurrence of said flow disturbance along said respective one of saidfirst and second flow paths, and for actuating said first drive meanssuch that said first drive means engages the other one of said first andsecond strapping materials so as to drive said other one of said firstand second strapping materials in said forward direction along the otherone of said first and second flow paths when said sensing switch meanssenses said withdrawal of said one of said first and second strappingmaterials from said respective one of said first and second flow pathswhereby downtime interruption of said strapping operation, due to saiddisturbance occurring along said respective one of said first and secondflow paths, is minimized.
 4. Apparatus as set forth in claim 3,wherein:said first and second flow paths comprise two convergent flowpaths having separate, first and second inlet portions, and a singleoutlet portion.
 5. Apparatus as set forth in claim 4, wherein said firstdrive means comprises:first and second fixed drive rolls respectivelydisposed within the vicinity of said first and second inlet portions ofsaid first and second flow paths; and third and fourth drive rollscomprising a single assembly pivotable between first and secondpositions whereby said third and fourth drive rolls can respectivelycooperate with said first and second fixed drive rolls for respectivelydriving said first and second strapping materials along said first andsecond flow paths.
 6. Apparatus as set forth in claim 3, wherein:saidsensing switch means comprises a pair of sensors respectively disposedalong said first and second flow paths for respectively sensing leadingportions of said first and second strapping materials.
 7. Apparatus asset forth in claim 3, wherein:said second drive means comprises a singledrive roller interposed between said first and second supply coils. 8.Apparatus as st forth in claim 7, wherein:said single drive roller ismounted upon a free end of an arm pivotably mounted upon a housingportion of said apparatus; and a pair of solenoids are operativelydisposed upon opposite sides of said arm for pivotably moving said armin one of two opposite directions as said pair of solenoids areselectively energized so as to selectively engage said single driveroller of said second drive means with said first and second supplycoils.
 9. Apparatus for strapping package elements, comprising:a firstsupply coil of strapping material; a second supply coil of strappingmaterial; a first flow path for a first strapping material wound uponsaid first supply coil and leading from said first supply coil to astrapping sealing unit; a second flow path for a second strappingmaterial wound upon said second supply coil and leading from said secondsupply coil to said strapping sealing unit; a first drive meansselectively engageable with said first and second strapping materialsfor driving a selected one of said first and second strapping materialsin a forward direction along a respective one of said first and secondflow paths from a respective one of said first and second supply coilsto said strapping sealing unit; a second drive means selectivelyengageable with said first and second supply coils for driving aselected one of said first and second supply coils in a reversedirection so as to retract one of said first and second strappingmaterials out from a respective one of said first and second flow pathswhen said one of said first and second strapping materials is depletedupon said selected one of said first and second supply coils; a firstsensing switch means for sensing depletion of said one of said first andsecond strapping materials upon said selected one of said first andsecond supply coils, and for actuating said second drive means fordriving said selected one of said first and second supply coils in saidreverse direction so as to retract said one of said first and secondstrapping materials out from said respective one of said first andsecond flow paths; and second sensing switch means for sensing a leadingend portion of said one of said first and second strapping materials assaid one of said first and second strapping materials is withdrawn fromsaid respective one of said first and second flow paths as a result ofsaid driving of said selected one of said first and second supply coilsin said reverse direction in response to said sensing of said depletionof said one of said first and second strapping materials upon sadselected one of said first and second supply coils, and for actuatingsaid first drive means such that said first drive means engages theother one of said first and second strapping materials so as to drivesaid other one of said first and second strapping materials in saidforward direction along the other one of said first and second flowpaths when said second sensing switch means senses said withdrawal ofsaid one of said first and second strapping materials from saidrespective one of said first and second flow paths whereby downtimeinterruption of said strapping operation, due to said depletion of saidone of said first and second strapping materials upon said selected oneof said first and second supply coils, is minimized.
 10. Apparatus asset forth in claim 9, wherein:said first and second flow paths comprisetwo convergent flow paths having separate, first and second inletportions, and a single outlet portion.
 11. Apparatus as set forth inclaim 10, wherein said first drive means comprises:first and secondfixed drive rolls respectively disposed within the vicinity of saidfirst and second inlet portions of said first and second flow paths; andthird and fourth drive rolls comprising a single assembly pivotablebetween first and second positions whereby said third and fourth driverolls can respectively cooperate with said first and second fixed driverolls for respectively driving said first and second strapping materialsalong said first and second flow paths.
 12. Apparatus as set forth inclaim 9, wherein said first sensing switch means comprises:a reflectiveelement disposed upon a core portion of each one of first and secondstrapping material supply rolls upon which said first and secondstrapping material supply coils are wound; and a photoelectric celldisposed externally of an outer peripheral portion of each one of saidfirst and second strapping material supply rolls for detecting saidreflective element of one of said first and second strapping materialsupply rolls when said one of said first and second strapping materialsupply rolls is depleted of said respective first and second strappingmaterial.
 13. Apparatus as set forth in claim 9, wherein said secondsensing switch means comprises:a pair of sensors respectively disposedalong said first and second flow paths for respectively sensing leadingportions of said first and second strapping materials.
 14. Apparatus asset forth in claim 9, wherein said second drive means comprises:a singledrive roller interposed between said first and second supply coils. 15.Apparatus as set forth in claim 14, wherein:said single drive roller ismounted upon a free end of an arm pivotably mounted upon a housingportion of said apparatus; and a pair of solenoids are operativelydisposed upon opposite sides of said arm for pivotably moving said armin one of two opposite directions as said pair of solenoids areselectively energized so as to selectively engage said single driveroller of said second drive means with said first and second supplycoils.